This invention relates to a vibration-isolating device used to support a vibration generating source such as vehicle engine for the purpose of vibration isolation.
A liquid-in vibration isolator has been known as a mount supporting a vibration generating source such as vehicle engine so as not to transmit its vibration to a vehicle body (for example, JP-A-9-89037, JP-A-10-9330).
The vibration isolator of such type is configured so that a cylindrical body fitting attached and fixed to the support side and an upper side attachment fitting attached to the side of the vibration generator such as engine are connected via a thick vibration isolating substrate made of a rubber material with external contour in the form of nearly truncated cone, a diaphragm is further disposed at the lower side of the body fitting opposite to the vibration isolating substrate, there are liquid-in chambers between the vibration isolating substrate and the diaphragm, the liquid-in chambers are divided into two liquid chambers on the side of the vibration isolating substrate and the diaphragm by means of a partition member, both liquid chambers are passed through by an orifice, the vibration damping and vibration isolating functions are fulfilled by the liquid flowing effect between both liquid chambers produced by the orifice and the vibration suppressing effect of the vibration isolating substrate.
The vibration isolator of this kind provides a stopper mechanism to restrain the displacement of more than the predetermined level of the upper side attachment fitting when the vibration isolating substrate is deformed due to vibration of engine and the like and the upper side attachment fitting moves in the up-and-down direction and the fore-and-aft direction square to the axial direction.
In the case of conventional apparatus, the stopper mechanism is constructed so that, with a flange for the stopper extending radially provided for the upper side attachment fitting, a cylindrical stopper fitting extending outside the vibration isolating substrate above the flange, the upper end of which is inwardly folded and formed so as to be located above the flange, is fixed to the cylindrical body fitting to act stopper function.
With the use of this stopper mechanism, in time of large displacement in the upward direction or square to the axial direction (fore-and-aft or lateral direction) accompanied by vibration, the flange for the stopper abuts the folded extremity or the side wall in the form of an inner flange at the upper extremity of the stopper fitting to restrain movement of the upper side attachment fitting more than a certain level, and the upper side attachment fitting is difficult to be released (falling off) when a vehicle comes into collision, etc. Thus, the stopper mechanism brings about high reliability in strength.
Incidentally, in the stopper mechanism, a relatively thick stopper rubber is provided on the top surface and outer circumferential portion of the flange abutting against the stopper fitting by the vulcanization adhering means for the purpose of shock absorption at the time of abutting. This stopper rubber is made up of a rubber integral to the vibration isolating substrate vulcanization-adhered to the upper side attachment fitting, and provided to circumferentially and continuously envelop the outer circumferential portion and the top surface of the flange. In particular, at the top surface side rubber portion of the stopper rubber, the stopper rubber is circumferentially and continuously in the form of convex against the top surface of the flange, its inner portion being in the form of concave. Besides, thickness of the stopper rubber becomes to some degree from the viewpoint of effect of shock absorption, etc. at the time of abutting.
Therefore, with the vibration isolator loaded in a vehicle, rainwater, etc. intruded from an opening at the top of the cylindrical stopper fitting gets in the inner concave through the stopper rubber at the top surface of the flange of the upper side attachment fitting, easily being accumulated without being discharged. Being accumulated, the water becomes rotten to easily cause corrosion or rust, and it is apprehended that the vibration isolating substrate or stopper rubber made of a rubber material may change in quality or be deteriorated.
There may be concave grooves formed on the top surface side rubber portion of the stopper rubber, radially at every required circumferential intervals. These concave grooves mainly serve to prevent abnormal sound caused at the time of adsorption at the stopper fitting, and its depth is not so deep, of the order of nearly half the thickness of the top surface side rubber portion, thus having not so much effect on discharging the intruded water.
Besides, the outer circumferential rubber portion of the stopper rubber extends radially from the top extremity of the vibration isolating substrate, increasing in diameter. That is, as against the outer circumferential rubber portion of the stopper rubber, the top extremity of the vibration isolating substrate below is in the shape of undercut. Therefore, since it is difficult to axially part the dies due to the undercut shape when the stopper rubber is formed simultaneously and integrally with the vibration isolating substrate, a split die must be used to form the outer circumference of the vibration isolating substrate.
The present invention provides a vibration isolator equipped with a stopper mechanism of the aforementioned configuration to have a stopper mechanism in the up-and-down direction and the fore-and-aft and lateral direction square to the axis, to be able to prevent water intruded into the top surface of a flange for the stopper from being accumulated, to be superior in durability, and to enable the dies to axially being parted even in the shape of undercut.
The vibration isolator of the present invention comprises a cylindrical body fitting, an upper side attachment fitting having the flange disposed at intervals upward an axis center of the body fitting and extended radially, a vibration isolating substrate made of a rubber material interposed between the body fitting and the upper side attachment fitting to connect both fittings, a cylindrical stopper fitting interconnected with the body fitting and extending outside the vibration isolating substrate up to above the flange, being folded inside so that the upper extremity portion lies above the flange, the top surface and outer circumferential portion of the flange provided with a stopper rubber, and is constructed so that the flange abuts the stopper fitting through the stopper rubber when the upper side attachment fitting moves largely in the upward direction or square to the axial direction accompanied by vibration, the stopper rubber having a notch groove for continuous drainage from the top surface to the outer circumferential portion at least one place circumferentially.
The vibration isolator serves the stopper function securely in time of large displacement in the upward direction or the fore-and-aft and lateral direction square to the axial direction under the condition loaded in a vehicle. Besides, if water such as rainwater intrudes from the top opening of the cylindrical stopper fitting and gets in the top surface of the flange of the upper side attachment fitting, the intruded water is drained through at least one notch groove for drainage formed on the stopper rubber provided around the top and outer circumferential portion of the flange without accumulating water on the top surface of the flange. Accordingly, corrosion or rust due to accumulation of water or change in quality, deterioration of vibration isolating substrate made of the rubber material or stopper rubber can be avoided, thus increasing the durability.
Furthermore, the stopper rubber is divided at least one place circumferentially by means of the notch groove. Therefore, since the stopper rubber is easy to be deformed as compared with circumferentially annular and continuous one, it is possible to part the dies axially even if an outside diameter of the stopper rubber is larger than the upper extremity of the vibration isolating substrate below the stopper rubber.
It is desirable that the notch groove for drainage has a depth substantially equal to or a little shallower than the thickness of the stopper rubber from the top surface to the outer circumferential surface, thus securely carrying out drainage action on the top surface of the flange.
It is also advisable to form the notch groove at one or a few places circumferentially. By doing so, the notch groove of the aforementioned depth being formed can adequately carry out the stopper function preventing elastic force of the stopper rubber from being excessively smaller. In particular, when the notch grooves are provided at two opposite places circumferentially, drainage action on the top surface of the flange can be carried out properly and securely, without excessively reducing the elastic force of the stopper rubber.
When one of the notch groove for drainage is located at the lowest level on the top surface of the flange while being loaded on a vehicle with a gradient, the intruded water will be drained further favorably.
As for the vibration isolator, it is desirable that the vibration isolating substrate is of nearly truncated cone, the upper extremity of the vibration isolating substrate is stuck to the lower surface of the flange of the upper side attachment fitting by means of the vulcanization adhering means, and that the stopper rubber is formed by the rubber material continuously from the upper extremity of the vibration isolating substrate. Accordingly, the stopper rubber can be formed simultaneously by the rubber material integral with the vibration isolating substrate, requiring no extra forming process, thus capable of producing it at lower cost.
In case where the outer circumferential rubber portion of the stopper rubber formed integral with the vibration isolating substrate as described above has larger diameter than the upper extremity of the vibration isolating substrate, it is desirable that the notch groove for drainage is formed nearly flush with the upper extremity of the vibration isolating substrate at the outer circumferential rubber portion of the stopper rubber.
Therefore, since the stopper rubber is divided at least one place circumferentially irrespective of the shape of the undercut at the upper extremity of the vibration isolating substrate below the outer rubber portion of the stopper rubber, the stopper rubber is easy to be deformed and the dies can easily be parted axially during the forming process.
Besides, as for the vibration isolator, it is desirable that the vibration isolating substrate is of nearly truncated cone, the lower extremity of the vibration isolating substrate is stuck to the upper portion of the cylindrical body fitting, and that a draining means is provided from the lower portion of the outside space of the vibration isolating substrate through outside of the vibration isolator. In particular, when an annular concave portion is formed between the outer circumferential lower portion of the vibration isolating substrate and the upper extremity inner circumferential surface of the body fitting, it is advisable to form a through-hole from the lower portion of the concave through the body fitting and the stopper fitting to the outside as a draining means. Consequently, since water falling from the upper surface of the flange through the notch groove for drainage can be drained through the draining means, for example, such as through-hole, to the outside of the vibration isolator, water is not accumulated in the space such as concave outside the vibration isolating substrate.
With regard to the vibration isolator, it is desirable, from the viewpoint of vibration damping function and vibration isolating function, that a diaphragm made of a rubber film is disposed opposite to the vibration isolating substrate at the lower side of the body fitting, that there is a liquid-in chamber between the vibration isolating substrate and the diaphragm, that the liquid-in chamber is divided into two liquid chambers at the vibration isolating substrate and the diaphragm by means of a partition member, and that both liquid chambers are connected by an orifice.